The present invention pertains to a device for erecting predominantly plane material blanks along prepared bending edges.
CN 2 330 502 Y discloses a device for producing boxes of punched blanks. This device comprises a magazine with a separating device for storing the plane punched blanks, a device with application nozzles for applying glue, a forming device for erecting a punched blank with glue applied thereon into a box, as well as transport devices for transferring the blanks between the aforementioned processing stations. The forming device comprises funnel-shaped guide elements for erecting the box, wherein these guide elements initially take hold of areas of the initially plane blank to be erected and then erect these areas relative to the base of the blank opposite to its transport direction.
The disclosed device furthermore comprises pivotable elements for folding over areas of the blank that are not taken hold of by the funnel-shaped guide elements such as, e.g., glue tabs.
A pressing device is arranged downstream of the erecting device and respectively accommodates one individual erected box in order to apply pressure upon its glued surfaces from outside by means of movable elements. The inner countersupport is formed by a plunger that pushes the blank into the pressing device through the erecting device with the described funnel-shaped guide elements.
During the transfer of the box from the erecting device to the spaced-apart pressing device, the box is only held on its inner side by the plunger with the aid of a suction element such that the glued joints may once again separate. This may lead to the glued surfaces no longer being aligned relative to one another such that the quality of the finished boxes is compromised. In addition, the box with the erected surfaces is moved in a sliding fashion on stationary elements such that markings are produced on the outer surfaces of the boxes due to the restoring forces acting in the bending edges.
In addition to these disadvantages that compromise the quality, the output of the proposed device is also very limited because the erection of a trailing blank can only take place once the glued joints of the leading box have cured to such a degree that the adhesive forces reliably exceed the restoring forces and the glued joints of the box can no longer separate during its removal from the pressing device. Only then can the plunger return into its home position and take hold of the next material blank during an ensuing work stroke.
CN 103 786 368 A discloses a device for producing boxes that are open on one side of plane material blanks by erecting the side areas. This device comprises a stationary annular die and a movable plunger that presses the plane material blank into the die. The forming inner contour of the die continues in a directly adjacent shaft that is composed of four stationary walls and receives already erected boxes. A first box located in the die is pushed forward in the shaft by a second box during the forming process thereof. This process is repeated such that the shaft is filled with a stack of boxes. The shaft is divided into two zones, wherein a first zone located adjacent to the die can be heated and a second zone can be cooled.
Although the boxes have a tendency to open due to the tensions introduced into the material blank by the forming process, they are prevented from opening in the shaft by the walls thereof. Since the shaft can simultaneously accommodate several boxes, the time available for stabilizing the desired shape of each box is at the same output multiplied in accordance with the capacity of the shaft. The stabilization of the box shape is additionally accelerated due to the purposeful temperature management in the transport direction.
The boxes push one another forward within the shaft against the friction on the shaft walls. This may lead to the boxes being glued to one another at certain locations such that they can no longer be separated from one another without being damaged. The significant friction between the boxes and the shaft walls caused by the tensions in the boxes leads to markings and damages of the boxes, particularly if the consist of sensitive materials.
The fact that a box remains in the shaft that stabilizes its shape until it is ejected by the trailing boxes results in the shaft always being filled with boxes such that the operating personnel must elaborately clear the shaft of boxes manually, e.g., prior to set-up processes.